Sunscreens are meant to block harmful ultraviolet rays but it turns out they don’t do a great job of it. In fact, the zinc oxide nanoparticles (NPs) that form the core ingredient in most sunscreens block a portion of these rays – called UVA – but they also emit some UVA of their own which then penetrates the dermal layer of the skin and enhances the generation of ‘cancer-inducing radicals’. Now, a team of scientists at IIT Bombay, led by Prof Ajit R Kulkarni, has come up with a more potent form of zinc oxide, called engineered zinc oxide nanoparticles (E-ZnO NPs) that promises to play a significant role in the science of sunscreen formulation.

Their work was presented at the 16th International Congress on Photobiology held in Argentina in September 2014 and is currently under review as an invited article to Pure and Applied Chemistry, the official journal of the International Union for Pure and Applied Chemistry.

“The normal zinc oxide particles currently used in sunscreens have the ability to screen a portion of the UVA, but the problem with such particles are their harmful UVA emissions. Therefore, to develop safer sunscreens, it was important that we eliminate this harmful UVA emission from these zinc oxide NPs,” says lead researcher Dr Adersh Ashok of the Centre for Research in Nano Technology & Science.

Dr Ashok said UVA, which is the main component of terrestrial UV radiation, damages DNA and other biomolecules due to its ability to generate ‘reactive oxygen species’ which damages human genetic material, thereby leading to cancer. A recent WHO report said one of every three cancer cases was of the skin and UV rays were a major culprit.

According to Dr Ashok, the new E-ZnO NPs can bypass harmful UVA emission while at the same time make it a “broadband UV absorber and broadband visible emitter”. “This visible emission is neither harmful nor dangerous for the skin when compared to UVA emission from normal zinc oxide NPs,” says Dr Mayuri N Gandhi of the Centre for Research in Nano Technology & Science at IIT Bombay and who is part of this research team.

The scientists also said E-ZnO NPs can impart a “brightening effect” or glow to the human skin. “The material developed by us has many advantages over existing ones. It is more transparent, gives a glow to the face, besides cutting off UVA and UVB rays. With its camouflaging effect, it will find its utility in wrinkle-free creams,” says Prof Kulkarni of the Department of Metallurgical Engineering and Materials Science.

The researchers are now looking for potential industrial partners for commercialising this work. “We are in talks with a few companies to take our research to the next level,” says Dr Ashok.